27.關於骨性錨定應用於成人矯正的敘述，下列何者錯誤？
(A)通常上顎牙弓可以後退2～4 mm
(B)上顎後牙壓入1 mm可關閉2～3 mm的前牙開咬
(C)壓入後牙來關閉前牙4 mm的開咬只需要1個月的時間
(D)牙周病患者在前牙壓入時有可能導致牙周囊袋的加深

Distal movement of the maxillary molars is one way to provide space in a crowded maxillary arch…..The entire arch usually can be moved back 2 to 4 mm. 利用骨性錨定來進行上顎牙弓後退是一個解決擁擠的方法…通常上顎牙弓可以後退2~4 mm。A正確

 Because 1 mm intrusion of maxillary posterior teeth should translate into about 2 mm of closure of anterior open bite, a 4-mm open bite often closes in as many months.上顎後牙壓入1 mm可關閉2 mm的前牙開咬，關閉前牙4 mm的開咬需要數個月的時間。B正確，C錯誤。

Intrusion of Incisors : One potential problem with intrusion in adults with periodontal involvement is the prospect that a deepening of periodontal pockets might be produced by this treatment.在成人前牙壓入的隱憂是有可能導致牙周囊袋的加深，D正確。